Low gold jewelry alloy

ABSTRACT

A jewelry alloy is disclosed preferably of 1 to 5 karat gold having the color, hue and shine characteristics of 10 or higher karat yellow gold. Although the alloy disclosed is virtually identical in appearance to 10 to 18 karat yellow gold, it is substantially less expensive and provides a relatively low cost substitute for higher karat yellow gold. The alloy has the following composition, by weight: Gold: 17-25% Silver: 10-27% Copper: 40-60% Zinc: 3-12% In addition to its appearance, the alloy disclosed has good corrosion and high tarnish resistance, good workability and castability and can be plated, if desired, and sized with conventional solders.

FIELD OF THE INVENTION

The subject invention is directed to alloys for use in making jewelry and, more particularly, to a gold alloy containing not more than about 15% by weight gold, more particularly, in the range of 3 to 6%, approximately for 1 to 2 karats.

BACKGROUND OF THE INVENTION

There had been an effort by workers in the art to develop gold alloys having the appearance of 10, 12, 14, and 18 karat gold but with a much lower gold content. However, many problems have been encountered in achieving the desired durability, workability, corrosion and tarnish resistance and particularly in simulating the appearance of yellow gold alloys as the percentages of gold have been decreased to provide a lower cost substitute for 10 and higher karat gold. Representative of the efforts of prior art workers are the following patents, U.S. Pat. Nos. 2,141,156; 2,141,157; 2,200,050; 2,216,495; 2,248,100; 2,576,738; 2,654,146; 4,266,973; and 4,276,086. It can be noted that these efforts have all been directed to gold alloys in the 8 to 20 karat range. For example, U.S. Pat. Nos. 2,141,156 and 2,141,157 to Peterson are directed to 8 to 14 karat gold alloys. U.S. Pat. No. 2,200,050 to Auwarter, U.S. Pat. Nos. 2,216,495, and 2,248,100 to Loebich are directed to gold alloys preferably in the 33-45% gold range or above 8 karats. U.S. Pat. No. 2,576,738 to Williams; U.S. Pat. No. 2,654,146 to Mooradian; U.S. Pat. No. 4,266,973 to Guzowski and U.S. Pat. No. 4,276,086 to Murao all deal principally in the 8 to 20 karat range.

The problems of providing a truly low cost substitute for 10 or higher karat gold having the desired color, hue and luster as well as other desirable properties such as resistance to corrosion and tarnishing as well as a reduction of surface roughness have heretofore not been overcome in the prior art. In particular, it has been observed that attempts to produce yellow gold alloys having a gold content in the 5 to 6 karat range have failed to produce an alloy having the color, hue and luster of known yellow gold alloys of 10 and higher karat while exhibiting the good corrosion resistance and surface smoothness also found in 10 or higher karat gold. Otherwise expressed, in the past unless the gold content of the alloy was above 35% of the total weight of the alloy the color, hue and luster thereof was unacceptable for use in the jewelry industry. Although attempts have been made to produce a gold alloy for use in jewelry production having a gold content or less than 30%, the aesthetic appearance of such alloys has generally not been comparable to 10 and higher karat gold. For example, although prior art patents can be found which speak of the broad range of gold content (not the preferred range) as having a lower limit of 25% gold (about 6 karats) e.g., U.S. Pat. No. 2,200,050 to Auwarter, such alloys have been found to clearly lack the color, hue and luster of 10 or higher karat gold. In addition, the Auwarter alloy must contain 2-6% palladium which prevents the alloy from being electropolished. As a result, it would have to be hand polished which takes a considerable amount of time and effort and does not give the quality of an electro-polished alloy.

SUMMARY OF THE INVENTION

The alloys of this invention contain less than about 15% by weight gold, but contrasted to prior art alloys nevertheless do have the color, hue and luster of 10 and higher karat gold and, in addition, exhibit good resistance to corrosion and tarnishing, are easily cast, are sufficiently malleable to be easily worked, can be electropolished, can be plated, if desired, can be sized with conventional solders, and can be remelted a number of times. The color, luster, shine and hue of the alloys of the present invention are substantially identical to that of 10 or higher karat gold. These properties are achieved by a yellow gold alloy having the following composition, by weight:

Gold: 3-6%, preferably about 4.17% Silver: 10-20%, preferably about 16.34% Copper: 40-80%, preferably about 64.1% Zinc: 10-20%, preferably about 15.33% Niobium: 0.01-0.05%, preferably about 0.03% Cobalt Chrome: 0.010-0.050%, preferably 0.025% Tantalum: 0.005-0.015%, preferably about 0.01%

The fine gold should be conductive, hypoallergenic, malleable, lustrous and dense. The silver should be conductive, heat treatable, malleable and lustrous. The copper is conductive and malleable. Zinc is conductive, lustrous and dense. The niobium is highly conductive, heat treatable, temperature stable, hypoallergenic and anticorrosive. The cobalt chrome is highly conductive, heat treatable, hypoallergenic and anticorrosive. Finally, tantalum is highly conductive, heat treatable, hypoallergenic and anticorrosive.

DETAILED DESCRIPTION OF THE INVENTION

The Gold One™ jewelry alloy of the present disclosure is a 1 KT Gold Alloy with unique characteristics for manufacturing fine jewelry, characterized as follows:

-   -   Hypoallergenic: Gold One™ is made of a combination of all         hypoallergenic metals to provide quality jewelry that will not         interact with the wearer's skin. This is an especially critical         benefit as it relates to the manufacturing of earring findings,         i.e., ear wires, posts, curved bars and earring clips.     -   Malleable: Prior to the hardening process after fabrication,         Gold One™ is a soft precious metal alloy that can easily be         shaped to intricately detailed rings, earrings, necklaces,         bracelets, pendants, chain, broached, watches and bands.     -   Hardening/Scratch Resistance: The combination of Silver,         Niobium, Tantalum and Cobalt Chrome creates a unique alloy with         advanced hardening properties by heat treatment resulting in a         stronger wear resistant metal.     -   Tarnish Resistance: The anti-corrosive properties of Fine Gold,         Niobium, Tantalum and Cobalt assist in suppressing the corrosive         reactions that typically lead to aggressive tarnishing in low         karat alloys.     -   Conductivity: The Combination of Fine Gold, Silver, Copper,         Zinc, Niobium, Cobalt Chrome and Tantalum creates a highly         conductive precious metal alloy. A minimum of 1.5-Micron 14 KT         to 24 KT Gold plating is electrically bonded to the outside of         this precious metal alloy to lock out oxidation reinforcing the         tarnish resistant properties of Gold One™.     -   Versatility: The Gold One™ Precious Metal Alloy can be used in         all manufacturing processes including Die Striking, Continuous         Casting, Tubing, Laser Printing, Rubber and Metal Mold Casting         and Electroform.     -   Polish and Luster: The Gold One™ Precious Metal Alloy results in         an easy to fabricate metal with reduced porosity, reducing the         amount of tumbling and polishing needed to achieve the desired         luster for fine jewelry. This quality adds efficiency to the         manufacturing process, cutting down lead times for order         completion and increasing production output.     -   Density: Gold One™ is a dense 1 KT Gold alloy that resembles the         density of typical 10 KT to 14 KT Gold Jewelry within a 10% to         30% range.     -   Affordability: 1 KT Gold Jewelry, made with the Gold One™ Alloy,         provides today's consumer with the most sought-after         aspirational jewelry at up to 80% savings from typical 14 KT         Gold Product.

The alloy preferably comprises (or consists of) Fine Gold: 4.17%—Conductive, Hypoallergenic, Malleable, Lustrous, Dense; Silver: 16.335%—Conductive, Heat Treatable, Malleable, Lustrous; Copper: 64.1%—Conductive, Malleable; Zinc: 15.33%—Conductive, Lustrous, Dense; Niobium: 0.03%—Highly Conductive, Heat Treatable, Temperature Stability, Hypoallergenic, Anti Corrosive; Cobalt Chrome: 0.025%—Highly Conductive, Heat Treatable, Hypoallergenic, Anti Corrosive; and Tantalum: 0.01%—Highly Conductive, Heat Treatable, Hypoallergenic, Anti Corrosive.

The alloy can be hammered, cast, rolled and made into wire. Thus, the alloy is capable of being formed into a variety of sizes and shapes by techniques traditionally used in the jewelry industry to form jewelry articles of a desired size and configuration. The alloy may also be cut and sized with solders conventionally used in the jewelry industry and can be plated with precious metals such as rhodium if desired.

The alloy may be melted in the 1000°-1100° C. range and cast and shaped with conventional techniques. One of the additional advantages of the alloy is that it can be melted six to seven times whereas 10 and higher karat gold can only be remelted about three or four times before it must be reconstituted.

Unlike known yellow gold alloys, the gold content of the subject invention in the preferred form does not exceed 15% but surprisingly exhibits good resistance to corrosion and tarnishing, good workability and surface smoothness as well as a color, luster, shine and hue at least comparable to 10 karat gold.

Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims. 

What is claimed is:
 1. A gold metal alloy of less than 4 karats having good tarnish and corrosion resistance, good workability and castability and a color, luster, shine and hue characteristics of higher karat gold containing alloys, the gold metal alloy consisting essentially of, by weight, 3-6% gold, 10-20% silver, 40-80% copper, 10-20% zinc, 0.01-0.05 niobium, 0.010-0.025% cobalt chrome and 0.005-0.02% tantalum.
 2. The gold alloy of claim 1, wherein the gold content is about 4% by weight.
 3. The gold alloy of claim 2, wherein the gold, silver, copper, zinc, niobium, cobalt chrome and tantalum have a weight of, respectively, 4%, 16%, 64%, 15%, 0.03%, 0.025% and 0.01%.
 4. A gold alloy of about 1 karat having good tarnish and corrosion resistance, good workability and castability and a color, luster, shine and hue characteristic higher karat gold containing alloys, the gold metal alloy consisting essentially of: 4.17% fine gold, 16.335% silver, 64.1% copper, 15.33% zinc, 0.03% niobium, 0.025% cobalt chrome and 0.01% tantalum.
 5. An article of jewelry formed of the alloy of claim
 1. 6. An article of jewelry formed of the alloy of claim
 4. 